Some of these posts were horrific. I'm so sorry people have been treated so badly by people :(
I don't really hold grudges, but I certainly don't forget!! Here are some:
-My school bullies. A couple of years after finishing school (i.e. I finished going to school, not that I went to a "finishing school"!), one of them came up to me, and was all friendly (like we were long lost mates). I told her how crap she made me feel, and how much I dreaded school because of her. To be fair, she did apologise.
-A teacher I had at secondary school. I spent the early part of my childhood abroad. We came to UK, and I went to a private school (you had to have an interview and pass entrance exams to get in there), as it followed a similar curriculum to the IS I'd gone to back home. I went to a grammar school in starting in Yr 9 (I sat entrance exam/had interview and passed both, but the school also went by the CE grades I got, and the school report from my Headmaster). That teacher had it in for me from when I started. I was a conscientious student, always respectful to teachers and always worked hard at school. The teacher was fab with other students but hideous to me. She used to ridicule me in class because I'd committed the crime of not sitting the 11+ exams (and that made me a target for some bullying). She implied that I was only there because of my Dad buying my place there (WTF?! that wouldn't have even been an option, and rightly so). She turned a subject I loved into one I hated (she taught our class up to Yr 11). Years later, my eldest sat the 11+. I checked the staff lists for the local grammar schools, and found she was still teaching at one of them. I didn't put that one down as an option, as I didn't want her anywhere near my DC.
I can never understand why teachers could be so awful to pupils. I'm in my 40's now, and remember all my teachers (I was lucky, they were mainly brilliant, and I'm still in touch with many even now). I have never forgotten this particular teacher though, and when I saw her name on the staff list, I felt sick.
-an ex that I dated years ago. Nice as pie to anyone he wasn't dating. An abusive, nasty POS to anyone he was dating. I'm so glad I got out of that, and I pity the person he's with now. He hasn't changed. Still blames the world for his issues.
-workplace bully for many years ago. Hideous, toxic cow. She was in my then manager's pocket and he turned a blind eye to her antics and shit. Several people left because of her. I retrained to a different career because of her (actually, I love what I do now, so that's a silver lining).
-XH. Long story, but the way he and OW behaved towards me when my lovely Dad died, I'll never forget. He came crawling back months later begging for another chance, I told him to sling his hook.
-XH's OW, ditto. She was meant to be my friend too. I had the last laugh though: they split some months later, and she came crying to me and looking for support. From me...after she had knowingly gone with my then H, and then treated me like shit. I told her what I thought of her.